Portland cement was invented in 1824 by Englishman Joseph Aspdin, which became and has remained the dominant cement used in concrete construction. Concrete consists of a hard, chemically inert aggregate substance composed of sand and gravel bonded by cement and water. Aggregates found in concrete can include sand, crushed stone, gravel, slag, ashes, burned shale, crushed glass, and burned clay. Fine aggregate (fine refers to the size of aggregate) is used in making concrete slabs and smooth surfaces such as floors, while coarse aggregate is used for large structures or sections of cement.
Over recent years, concrete and similar type flooring has enjoyed increasing popularity with expanding usage in both commercial and residential construction. Recent advances in polishing equipment and techniques allow contractors to grind and polish concrete or similar floor surfaces to a high-gloss finish that minimizes the need for waxes or coatings. If concrete is to be polished, an array of aesthetic options are available. Colored aggregate can be applied to the concrete mix or added to the top layer of the mix. Concrete treated in this manner can be polished to a smooth, high-luster finish and stained to resemble the look of polished stone surfaces such as marble, granite, tile, or terrazzo. To replicate the color of stone, stain or other dyes can be added to the concrete during the polishing process or integrally added to the concrete mixing process. The polishing process can reveal added aggregates, such as glass, seashells, nails, bolts, computer chips, or any other objects that can be mixed with the concrete and then polished smooth to achieve a wide variety of aesthetic appearances.
Generally, an internal impregnating sealer is applied during the polishing process that sinks into the concrete to protect the concrete by hardening and densify the concrete to eliminate any requirement for topical coating. This treatment of the concrete reduces maintenance significantly and creates a concrete floor that is much more durable compared to other traditional floor surfacing such as wood, linoleum, tile, vinyl, or even some types of stone. Many treatment solutions fill in small cracks, gaps, and voids to strengthen and densify the concrete. This strengthening of the concrete floor surface permits superior shine because the subsequent polishing of the surface removes smaller bits of surface material. Using polishing solutions can also help fill in pores, micro cracks, and fissures that are opened or exposed during the polishing process, and the polishing solution helps to lubricate and clean the pads used to polish the concrete and achieve a superior finish and shine.
One of the recent developments in the art contributing to the increasing popularity of polished concrete and stone flooring is the diamond-impregnated polishing pad. The industrial diamond abrasive incorporated into these pads greatly increases the effectiveness and the efficiency of the polishing process, so much so that existing floor polishing and grinding machines cannot fully exploit the potentials of these state-of-the art polishing pads.
The diamond-impregnated polishing pads are much more effective and capable of stripping off material from the exposed surface of concrete and stone flooring to achieve a very smooth, high luster, polished surface. The diamonds in the pads can dig into the extruding surface material to a much greater degree compared to earlier pad types and can strip the extruding layer of material off much easier compared to pads previously available. The diamond impregnated pads can also continue to remove material more effectively at a given smoother grade of pad (e.g. grit rating) and achieve a smoother finish than identically rated pads.
Newer diamond-polishing technology now makes it possible to grind and polish concrete surfaces at up to 3000-grit finishes. These finely polished concrete floors are essentially no-maintenance flooring. Removing all previous treatments and then polishing the floor can be a one-time fix that reduces maintenance costs, minimizing any requirement for expensive waxes or other coatings. After diamond polishing, the only maintenance required is the removal of dirt, oils, and other foreign substances that can stain the concrete.
Currently, most vendors of stone or concrete floor polishing services use a conventional single-pad rotary buffer machine operated by a single worker with a diamond-impregnated polishing pad attached. Such machines are limited in effectiveness because of the limited size of floor area that can be polished and grinded in a given period of time. The limited size of the buffer's polishing “footprint” is but one factor in the limited efficiency of a single operator using a floor buffer. This inefficiency extends in large measure from an inability to fully exploit the enhanced polishing and grinding properties of the diamond-impregnated pads.
Also, the conventional single-pad floor buffer cannot exert sufficient vertical force onto the floor surface for the pad to dig into and grip the upper surface layer of the floor material for maximum grinding. Nor can a conventional single-pad buffer develop sufficient rotational power to strip off the upper surface layer of the floor material to a sufficient degree. It is also cost prohibitive to polish a very large floor area to the degree of smoothness now possible with the newer type of pads. Moreover, if a conventional buffer machine could fully exploit the pads' potential, the forces exerted against the operator would be such that the operator could not control the buffer. As such, it is difficult for an operator to control the buffer and achieve a uniform finish over large areas, often leaving inclusions or “swirling” visible in sections of the flooring.
Earlier efforts to improve upon the ability to exploit diamond-impregnated pads has usually centered upon modifying floor scrubber machine designs for use in polishing and grinding concrete and stone floor surfaces. However, such efforts have not been successful. Such modified machines lack the necessary rotational power, cannot exert optimal vertical pressure, and cannot effectively dispense polishing solution. One prior art machine specially designed for concrete grinding and polishing is the Draygon RGS50. The RGS50 is not a satisfactory solution because it fails to adequately dispense water or polishing solution. It is limited in its grinding wheel configuration, and the amount of vertical force applied to the grinding surface is not well-regulated.
Thus, the RGS50 has trouble performing the grinding operation without leaving inclusions, swirling, or other imperfections in the surface. The RGS50 also has a limited capacity for water or polishing solution.
There remains a requirement for a machine that possesses sufficient engine power to rotate pads with sufficient rotational force and sufficient and regulated vertical force to dig into the floor surface to remove material to the extent that diamond pads make possible, to cover a greater surface area during operation such that it is possible to grind and polish floor surfaces to a superior smoothness with greater efficiency and at a reasonable cost, and to achieve a uniform finish that is free of inclusions or swirl patterns. There is also a need for a machine that offers the ability to quickly and easily change pads upon use or from a coarse to a finer grit rating. There is also a need for a machine that possesses a center liquid feed to distribute water and polishing solution. Finally, there is a need for a machine that can perform dissimilar grinding and polishing operations in a single pass to vastly improve the time efficiency of the task.